Tape is the cheapest. http://en.wikipedia.org/wiki/Magnetic_tape_data_storage http://en.wikipedia.org/wiki/Magnetic_tape_data_storage Prices don't show here,

Tape is the cheapest. http://en.wikipedia.org/wiki/Magnetic_tape_data_storage http://en.wikipedia.org/wiki/Magnetic_tape_data_storage Prices don't show here, but in general it's 15 times cheaper and 200 times less energy to use tape.